Flotation of sulfide ores

ABSTRACT

An improvement in the concentration of ores by flotation which comprises subjecting a sulfide ore in the form of a pulp to a flotation process in the presence of an effective quantity of a flotation collector comprising a thiocarbamate compound corresponding to the formula WHEREIN X comprises a chelating group and R is hydrogen or a hydrocarbon radical containing from 1 to 10 carbon atoms; R1 is an alkylene group, and R2 is a hydrocarbon radical usually containing from 1 to 7 carbon atoms. Certain of the indicated compounds provide enhanced selectivity and/or recovery of sulfide minerals of Cu, Zn, Mo, Co, Ni, Pb and As over iron sulfide.

llmted States Patent w13,590,999

72 1 inventors Wayne D. Gould FOREIGN PATENTS Miami, Ariz.: 187,116 12 1955 Austria .1 260/455 Guy H. Harris. Concord, Calif. g

[21] Appl No 799,119 I Primary Exammer-Frank W. Lutter [22 1 Filed Feb. 13, 1969 Assistant Examiner-Robert Halper [45] Patented i 6 1971 Attorneys-Griswold and Burdick, Bruce M. Kanuch and [73] Assignee The Dow Chemical Company a Norrls Midland, Mich.

' ABSTRACT: An improvement in the concentration of ores by flotation which comprises subjecting a sulfide ore in the form of a pulp to a flotation process in the presence of an effective quantity of a flotation collector comprising a thiocarbamate [54] FLOTATION 0F SULFIDE ORES compound corresponding to the formula 10 Claims, No Drawings H [52] |U.S.1Cl .L 209/166, l

R-'X Rl N"-fi OR2 [51] int. Cl 803d 1/02 [50] Field of Search .v 209/166,

167; 252/6 1; 260/455 wherein X comprises a chelating group and R is hydrogen or a hydrocarbon radical containing from 1 to 10 carbon atoms; R, [56] Reerences is an alkylene group, and R is a hydrocarbon radical usually UNITED STATES PATENTS containing from 1 to 7 carbon atoms. Certain of the indicated 116741166 /1 23 Douglass 209/166 compounds provide enhanced selectivity and/or recovery of 2,691,635 10/1954 Harris....... 209/166 X sulfide minerals of Cu, Zn, Mo, Co, Ni, Pb and As over iron 3,118,924 1/1964 Harman 260/455 lFlLO'llATlON F SULFIDE UlRlES BAC KGROUN D Flotation is a process of treating a mixture of finely divided mineral solids, e.g., a pulverulent ore, suspended in a liquid whereby a portion of such solids areseparated from other finely divided mineral solids, e.g. clays and the like materials present in the ore, by introducing a gas (or providing a gas in situ) into the liquid to produce a frothy mass containing certain of the solids on the top of the liquid, and leaving suspended (unfrothed) other solid components of the ore.

Flotation is based on the principle that introducing a gas into a liquid containing solid particles of different materials suspended therein causes adherence of some gas to certain suspended solids and 'not to others and makes the particles having the gas thus adhered thereto lighter than the liquid. Accordingly, they rise to the top of the liquid to form a froth.

Various flotation agents have been admixed with the suspension to improve the frothing process. Such added agents are classed according to the function to be performed: collectors, e.g., high carbon chain compounds such as collectors for sulfide minerals including xanthates, thionocarbamates, and the like; frothers which impart the property of forming a stable froth, e.g., natural oils such as pine oil and eucalyptus oil; modifiers such as activators to induce flotation in the presence of a collector, e.g., copper sulfate; depressants, e.g., sodium cyanide, which tend to prevent a collector from functioning as such on a mineral which it is desired to retain in the liquid, and thereby discourage a substance from being carried up and forming a part of the froth; pH regulators to produce optimum metallurgical results, e.g., lime, soda ash and the like.

it is of importance to bear in mind that additaments of the above types are selected for use according to the nature of the ore, the mineral sought to be recovered, and the other additaments which are to be used in combination therewith.

An understanding of the phenomena which makes flotation a particularly valuable industrial operation is not essential to the practice of the present invention. They appear, however, to be largely associated with selective affinity of the surface of particulated solids, suspended in a liquid containing entrapped gas, for the liquid on one hand and the gas on the other.

The flotation principle is applied in a number of mineral separation processes among which is the selective separation of such minerals as sulfide copper minerals, sulfide zinc minerals, sulfide molybdenum minerals and others from sul fide iron minerals. The present invention concerns the use of an unique class of compounds as collection agents in a flotation process. With some of these collectors, better recoveries are realized and with others improved selectivity is achieved. Certain of these agents produce improvement in both aspects.

SUMMARY The present invention concerns an improved method of flotation separation of sulfide minerals which comprises subjecting a sulfide ore to a flotation process in the presence of a compound corresponding to the formula wherein R represents H, or a hydrocarbyl radical containing from 1 to carbons, R is a divalent hydrocarbon moiety containing from I to 7 carbons, R is a hydrocarbyl radical containing from I to 7 carbons and X is a chelating group.

These compounds are useful as flotation collectors in flotation processes for the concentration of sulfide minerals such as copper, zinc, molybdenum, cobalt, nickel, lead and arsenic from ores in preference to other minerals.

PREFERRED EMBODIMENTS in the practice of the present invention, the defined class of compounds are employed as flotation collectors using stan dard flotation technique. Preferably, the compounds employed correspond to the formula wherein X corresponds to a chelating group selected from the group consisting of l -O-, --S-, S0, and S02;

R corresponds to H (when X is other than l $0 or $02 or a hydrocarbyl radical selected from the group consisting of an alkyl or alkenyl group, preferably containing from 1 to 10 carbon atoms, an aryl, cycloalkyl, aralkyl, alkaryl or an aralltenyl group; R, corresponds to an alkylene group, preferably containing from 1 to 5 carbon atoms, and R corresponds to a hydrocarbyl radical selected from the group consisting of an alkyl or an alkenyl group preferably containing from 1 to 7 carbon atoms, a cycloalkyl, cycloalkenyl, aralkyl, or aralkenyl group. Preferably R represents H when R contains 3 or more carbon atoms and X is other than l SIO or T02.

It appears that the presence of the chelating group in the flota tion collector compound as defined herein allows for better and more selective flotation of certain sulfide minerals over the use of otherwise similar thiocarbamate flotation collectors heretofore employed.

The flotation collector compounds as defined herein are particularly effective in flotation processes used to separate and concentrate copper sulfide and similar minerals from sul fide ores. ln such process, a pulp is first prepared by wet grinding a sulfide containing ore to a suitable particle size, with or without a pH modifier. A suitable frothing agent is then added, e.g., pine oil, cresylic acid, polyalkoxyparaffin and the like. An effective quantity of the flotation collector compound, as defined herein, is then added in an amount usually ranging from about 0.01 lb. to about 0.25 lb. per ton of pulp and the pulp is then agitated and aerated. The copper sulfide minerals and other like sulfide minerals collect as a froth which is readily overflowed or skimmed off from the residual gangue and nondesired materials and the metal values therein recovered.

The following Examples will facilitate a more complete understanding of the present invention but they are not meant to limit the scope of the invention to the specific embodiments incorporated therein.

EXAMPLE 1 Various species of flotation collector compounds within the scope of the present invention were employed in the flotation recovery of copper values from a sulfide ore obtained from South America employing the following procedure: An ore sample was wet ground for 5 minutes at 66 percent by weight solids with no other reagents. The pulp was then conditioned for 8 minutes by mixing with 0.12 lb./ton ofa flotation collector to be evaluated and 0.13 lb./ton of a standard frother. During the conditioning period, the pH was adjusted by the addition of a mineral acid to a value of about 3.8. The pulp was then floated by aeration for 7 minutes and the tailings assayed for copper.

Employed as a control for comparison purposes was a standard flotation collector compound consisting of a thiocarbamate compound corresponding to the formula:

0. l6 lb./ton ofa standard frother at a pH of 10.5. The pulp was then floated 8 5e minutes and the tailings assayed for copper. The collector composition and results obtained are set forth in the following Table ll The same control flotation collector 5 was employed as in Example l. H H H s CH: H-CCNCOC EXAMPLE3 H H CH3 in this example, copper sulfide and molybdenum sulfide 1 containing ores were treated in a manner similar to that The specific collector compounds of the present invention described in the foregoing examples. Used as controls were employed, and recoveries are set forth in the following Table l the prior art flotation collector employed in Example 1 (Con- TABLE I Percent Percent Nfiiber Collector ia l l co v r eii- Control Control 0.289 84.2

8 CH 1 H COCHgCH CH;I \'-COCH 0. 230 88.0

H S OH: 2 H3C-S-CHzCH2-I T -OC 0.294 83.5

H CH; 3 H CSCH2CHzZ IC-OCH CH Cfi 0. 235 87.2

s 4 H1 C5SCH2CHgNCOCH:CH 0.250 86.5

CH 5 .r H CSCH; CH:CH1IL-( IOCfi 0.308 83.1

H CH3 6 HgC-S-CI :CH9CH2CH2-OCH 0.281 84.6

0 H S 7 H3C -CHgCHgCHg-IL--O-CHgCHg 0.267 86.3

r 2 8 H C-O-CH:CH NC-OCH 0.233 87. 4

CH I B 9 HSCH CH NCO-CH 0.247 86. 7

H s GHQ: 10 SCHgCHzI I-%OCI 0.245 86. 7

CH; i i W 11 CH SCHgCHgN-COCH 0.238 87.1

It will be observed that the flotation collectors of the inventrol l) and a second collector (Control 2) corresponding to tion performed as well as, or better than, the control collector. the formula:

EXAMPLE 2 S OH:

I! Some of the collectors employed in Example 1 were further HN C O Cg tested on a copper sulfide ore obtained from the Southwestern United States. The ore sample was ground for 4 '7; minutes at 59 percent solids with 2.0 lbs./ton of lime. The pulp was conditioned for 2 minutes with an amount ofa specific collector and TAB L E ll a Percent Percent Run No. Collector Compound d ia il 381;

(.Iontrol.... Control .0025 0.330 50. 6

t? 1 incocnzcumcocanon. .0025 0.305 63.6

as 2 nacscmomri'cocmcnm .0025 0.261 68.1

Control Control .0125 0.288 66. 1

n 3 H 0OCHQCH CHgNCOCHgCH CHQ2 .0125 0.240 71.0

5 4 HgCSCH2CHQNCOCHQCHQCH(CH3)2 .0125 0.215 74.2

5 HnCaS CHzCHT-NGOCHgCH; .01 5 0. 259 68- o 6 H3CSCH2CH2CH2NCOCH(CHQ)2 .0125 0.239 71.2

HS 7 HS CH2CH21 IgOCH(CH3)2 .0125 0. 268 67.5

n 8 SCH2CH2NCOCH(CH3)QB .0125 0.235 71.

l !l 9 CH2SCH2CH2NCOCH(CH3)Q .0125 0.240 71.1

pound having the formula: S

H S M+S l 0 R2 The process conditions and results of this study are tabulated in following Table Ill.

wherein R is the same as defined hereinbefore, and M is an alkali metal cation, with an amine containing a chelating group in the carbon chain corresponding to the general formu- TABLE 111 Cone. of minerals in Amount feed stock, Recovery, 01 collec- Standard Diesel percent percent Tails, percent tor, 1b./ frother, oil, Ore source Collector ton pulp lb./ton 1b./ton pH Cu Mo Cu Mo Cu Mo South America Control (1) 0.06 0.134 0.033 4.5 19.27 0.330 84.66 61.78 0.281 0. 0164 L ll Do H3COCH2CHQCH2NCOCH(CHK)E 0.06 0.134 0.033 4.5 19. 76 0.326 89.00 62. 59 0.202 0.0164

Southwest U.S.A Control (2) 0.01 0.100 0.00 8.5 11.93 0.305 68.16 85. 48 0.265 0. 0032 n Do IIgcOcIi2C1I2C1 2NCOCH(C 3)2 0. 01 0.110 0.00 8.5 15.20 0.469 74.23 86.71 0.213 0.0029

EXAMPLE4 la R-QT-TENHQ wherein 1?, X and R are the same a s A zinc sulfide containing ore was treated as in the foregoing examples employing the same control collector as in Example 1 and a collector compound within the scope of the present in- 60 vention corresponding to the formula:

HQC H S defined hereinbefore.

Still other collectors of the invention are obtained by multistage preparative reactions. For example,when a thiol TABLE IV Amount of Standard collector, frother, Pine oil, CuSO4, Cone, Recovery, Tai Orc source Collector lb./ton 1b./ton 1b./ton lb./ton percent Zn percent Zn percent Zn Eastern Canada Control 0. 039 0. 028 0. 045 0. 30 14. 87 58. 1 1. 15 o New collector. 0. 033 0. 024 0. 043 0.55 20. 57 89. 9 0. 41

Flotation collectors as defined herein are prepared by several methods well known in the art. For example, the com 75 pounds are prepared by the reaction ofa xanthate compound corresponding to the general formula compound corresponding to the formula RSH, wherein R is the same as hereinbefore defined, is contacted with ethylenimine, as amine compound corresponding to the formula RS IH CH NH is formed. This product is then contacted with a xanthatc ester to prepare a compound within the scope of the present invention corresponding to the formula wherein R is the same as defined hereinbetore. Other amine compound starting materials can be prepared by methods well known in the art. For example, reference may be made to Wagner 8L Zook, Synthetic Organic Chemistry PP 787796, 1

wherein Y is H or a lower alkyl, is reacted with an alcohol or thiol compound corresponding to the formulas ROl-l, RSH respectively, wherein R is the same as defined hereinbefore, to prepare compounds corresponding to the formulas ROCILCHY-N, RSCH,CHYCN, respectively. These compounds are then contacted with a reducing agent such as LiAlH or H over a catalyst to provide compounds corresponding to the formulas Y R cmoHcHi-xm and Y RSCHgHCH NH:

respectively. These products are then reacted with a xanthate ester to provide products corresponding to the formulas I i ROCHfittyCHQI-COR, and

respectively, wherein R is the same as previously defined.

The xanthates starting materials can be prepared by reacting a solution of an alkali metal hydroxide or alkoxide in an alcohol corresponding to the formula R Ol-l, wherein R is the same as defined hereinbefore, with carbon disulfide (CS and then with methyl chloride to provide a xanthate compound corresponding to the formula wherein R is the same as defined hereinbefore. Other starting materials and process schemes can also be employed in preparing the flotation collectors useful in the process of the present invention.

One species of a flotation collector for use in the process of the scope of the present invention, corresponding to the for- CH: CH;

was prepared by adding 19.2 grams of technical grade methyl isopropylxanthate to l5.2 grams of a compound corresponding to the formula reacted with 4-bromobutyronitrile to give a compound which, when reduced with LlA1H gave an amine starting material corresponding to the formula CH S-(Cl-l ),,NH To 10.5 grams of methyl isopropylxanthate was added 8.3 grams of the amine starting material After the spontaneous evolution of CH SH had subsided, the reaction mixture was heated on a steam bath for about 3 hours. At the end of this period, the remaining CH SH was removed by heating the reaction mixture to 70 C. under a 20 mm. reduced pressure and the result- 0 ing product separated.

This compound is useful as a flotation collector in the flotation separation of sulfide mineral containing ores.

Another collector compound corresponding to the formula was prepared as follows: To 250 ml. of alcohol was added 3 grams of NaOH and to the resulting solution was added 13 grams (0.075 moles) of mixture was added 10.2 grams (0.068 mole) of methyl ethylxanthate, and the resulting mixture refluxed until the evolution of Cl-l SH ceased. The excess base was neutralized with CO and the reaction mixture was evaporated to dryness. The resulting residue was extracted with chloroform, filtered, and the filtrate evaporated to dryness. The product was recrystallized from isopropanol. The product yield was 12.5 grams ofa solid which had a melting point range of about 70.5-7 1 .5 C. This compound is also useful as a flotation collector in sulfide mineral flotation processes.

In a manner similar to that described directly above, 3- methylsulfenyl propyl amine is reacted with methyl ethylxanthate to provide a compound corresponding to the formula This compound can also be employed as a flotation collector in typical mineral sulfide flotation processes.

Examples of other alcohols which can be employed in the above preparations of the collector compounds include, cyclohexanol, cyclohexenol, allyl alcohol, cinnamyl alcohol, crotyl alcohol; 2, 3, 5-trimethyl-3-hexanol and 2,3,4- trimethyl-2-hexanol.

Examples of amine compounds which can be employed in the preparation of collector compounds include Xanthate compounds which can be employed in place of those described above to prepare collector compounds of the invention herein, by other methods known in the art include, for example and the like.

Other compounds useful as flotation collectors, are prepared in a manner similar to those set forth hereinbefore and are characterized by the general formula I; s R x-R1:'-rt2-o R wherein R, X, R and R are as set forth in the following Table V.

Various modifications may be made in the present invention without departing from the spirit or scope thereof for it is understood that we are limited only as defined in the appended claims.

We claim:

1. In the process of concentrating sulfide ores by froth flotation in the presence of a flotation collector the improvement which comprises:

a. contacting the sulfide ore in the form of a pulp with a flotation collector comprising a compound corresponding to the formula wherein R represents a member selected from the group consisting of H, an alkyl, alkenyl, aryl, aralkyl, aralkenyl, cycloalkyl, alkaryl or a cycloalkenyl group; R is an alkylene group containing from 1 to 5 carbon atoms; R is a hydrocarbyl radical selected from the group consisting of alkyl, alkenyl, cycloalkyl, cycloalkenyl, aralkyl or an aralkenyl group and X" represents a chelating member selected from the group consisting of -o -s-, so and so;

and the compound is further characterized in that when X is a member selected from the group consisting of S0 or S0 R is not H.

2. The process as defined in claim 1 wherein R represents a member selected from the group consisting of H, an alkyl or alkenvl oroun containin from I to lfi'carhon atoms R.. is a member selected from the group consisting of alkyl or alkenyl groups containing from 1 to 7 carbon atoms and X represents achelating member selected from the group consisting of and the compound is further characterized in that when X is a member selected from the group consisting of I $0 or $02, RisnotH.

5. The process as defined in claim ll wherein the flotation collector is a compound corresponding to the formula HS l// (OHahCHSCHgCHgNCOCH(CH3) 6. The process as defined in claim 1 wherein the flotation collector is a compound corresponding to the formula I; s CH SCH CH I IC OCH CH CH(CH )g 7. The nrnress as defined in claim I wherein the flotation collector is a compound corresponding to the formula collector is a compound corresponding to the formula u s H s r. Ins CH CILCHA' C c mum); 0 H 5 @11 0 {Ine 0 C H(CHQ)Q 8. The process as defined in claim 1 wherein the flotation 5 U collector is a compound corresponding to the formula 10. The process as defined in claim 1 wherein the flotation H collector is a compound corresponding to the formula l H;CO-CH;CH2CH;'NC-OOH 9. The process as defined in claim 1 wherein the flotation OH; 

2. The process as defined in claim 1 wherein R represents a member selected from the group consisting of H, an alkyl or alkenyl group containing from 1 to 10 carbon atoms, R2 is a member selected from the group consisting of alkyl or alkenyl groups containing from 1 to 7 carbon atoms and X represents a chelating member selected from the group consisting of and the compound is further characterized in that when X is a member selected from the group consisting of R is not H.
 3. The process as defined in claim 1 wherein from about 0.01 to about 0.25 pound of said collector is employed per ton of ore pulp treated.
 4. The process as defined in claim 1 wherein the flotation collector is a compound corresponding to the formula
 5. The process as defined in claim 1 wherein the flotation collector is a compound corresponding to the formula
 6. The process as defined in claim 1 wherein the flotation collector is a compound corresponding to the formula
 7. The process as defined in claim 1 wherein the flotation collector is a compound corresponding to the formula
 8. The process as defined in claim 1 wherein the flotation collector is a compound corresponding to the formula
 9. The process as defined in claim 1 wherein the flotation collector is a compound corresPonding to the formula
 10. The process as defined in claim 1 wherein the flotation collector is a compound corresponding to the formula 